You know, I have always wondered about that, and I was hoping that
somebody would set me straight on it.
As I was building this SB-220, I was thinking how much the components
reminded me of the inside of an antenna tuner. That led me to wonder
if that wasn't what I was actually doing, tuning the tube output
impedance to whatever the antenna system impedance was.
In that case, I wonder why people use tuners at all with these old
amplifiers. Does it give you more range, or something? Or is it
totally unnecessary?
Thanks,
Jeff/KD4RBG
---- Original message ----
>Date: Mon, 2 Mar 2009 21:29:13 -0500
>From: "Keith Schreiber" <schreiber@windstream.net>
>Subject: SWR & other things...
>To: <amps@hidden-valley.com>
>
> Hey Jeff!
>
> re: your query about the SWR range an SB-220 can
> handle...
>
> Not to worry OM. You'll know soon enough if the amp
> can't handle it - and if you do hear a little
> spitting or arcing, just STOP. Think of it this
> way: The pi-net output circuitry in a tube
> amplifier (or transceiver) IS an antenna tuner !
>
> I started in 1962, and back then, many hams didn't
> even own an SWR bridge. We tuned maximum antenna
> current using an RF ammeter. We just tuned for
> maximum antenna current. Very few hams realized
> that the pi-net output circuitry in their amps were
> really doing the impedance matching - just like an
> antenna tuner would do.
>
> Vy 73 de W8KTH
> Keith
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